When an operator designs a hydraulic fracturing stimulation treatment, two basic design tools are available: fracture design simulators and reservoir production simulators. Essentially all other information obtained will be intended as "enhancements" to one or both of these simulators. Minifrac tests will help identify formation pressure response and fluid loss coefficients used by the desigh simulator. If a 3-D design simulator is used, stress data from microfrac tests or mechaftical properties logs will be needed. Information from previous stimulation treatments such as production results, treating pressure response, pre-frac and post-frac pressure build-ups and post-frac tracer surveys are also used to improve modeling with the simulators.
The most recently available "enhancements" for the design and production simulators are the development of more accurate and realistic data bases for fracture conductivity and non-darcy flow effects. Data are now available that were generated under test environments that better simulate in situ reservoir conditions.
This paper illustrates how treatment designs are altered when the design simulator and the reservoir simulator use the new data for conductivity and consider non-darcy flow effects. It is clear that many treatment designs have beeii too conservative as to volume of proppant considered adequate. Also, the criteria for choosing a more costly proppant than sand require conductivity data and consideration of non-darcy flow effects. By incorporating the use of computerized economic analyses, the effect of using a more accurate data base for fracture conductivity values is studied.
The use of total stimulation cost considerations in the selection process gives a more accurate assessment of the economics than previously published studies, which often have considered only one variable (such as proppant cost) in their economic analysis.
In this paper, examples are included for shallow, intermediate depth, and deeply buried gas reservoirs, with several well conditions and treatment conditions varied to broaden the application of the resulting economic analyses.